Fish oils contain polyunsaturated fatty acids that are considered essential for preventing several diseases, some of which have neurological effects that promote growth in children. The overall objective of this study is to extract and characterize the oils in the fresh muscles of Schilbe grenfelli Linné, 1758 fish caught in the Malebo Pool (Congo River) in the Democratic Republic of Congo in order to highlight the nutritional value of the oils present in the muscles of this fish. The oils were extracted using the Soxhlet method and then characterized by thin-layer chromatography. The results obtained show that the muscles of S. grenfelli fish contain essential oils rich in polyunsaturated fatty acids of the omega-3 and 6 group, which allow this fish to be classified as fatty based on the average yield (46.62±2.1%) of oil extracted from its muscles. Analysis of the samples using thin-layer chromatography shows frontal ratios slightly higher than that of synthetic omega tri (0.80 cm). The results obtained show that the fresh muscles of Schilbe grenfelli fish are likely to offer good quality oils that are medically and nutritionally important for the Congolese population. Consumption of this fish meat is likely to contribute to the fight against cardiovascular disease and malnutrition, given the quality of these oils.

The main objective of this study was to assess the level of mercury, cadmium and lead contamination in two species of smoked fish, Protopterus dolloi Boulanger, 1900 and Chanallabes sp, sold in the Baramoto market and widely consumed in the city of Kinshasa in the Democratic Republic of Congo. A total of 60 fish samples (30 for Protopterus dolloi and 30 for Chanallabes sp) were taken and measured using atomic absorption spectrophotometers and molecular absorption spectrophotometers. The results of the toxicological analyses revealed the presence of the three trace elements in the muscles and heads of these two species of fish in varying concentrations. The highest concentrations were found in the Protopterus dolloi species (Hg: 0.79±0.1 µg/L, Cd: 0.41±0.32 µg/L, Pb: 0.33±0.01 µg/L). However, the concentrations found in both species of fish were below the maximum limits of the standard recommended by the WHO (Hg ˂ 10 µg/L; Cd ˂ 0.5 µg/L; Pb ˂ 1 µg/L). Despite the low levels found in the muscles and heads of the fish considered in this study, regular consumption of the flesh of these fish represents a public health hazard for the population of Kinshasa, and exposes consumers to multiple risks. Further studies on the quality of smoked fish should be conducted to ensure food safety for consumers.

The systematic inventory of the fish fauna of the Lukunga river and the characterization of the abiotic parameters at the fishing stations were carried out between January and June 2016. Six hundred and twenty-one fish were captured using artisanal techniques and identified belonging to 11 species, 7 kind and 4 families. Tilapia tholloni, Hemichromis elongatus and Hemichromis stellifer were the most represented with proportions of 16.91%, 16.43% and 12.08% respectively of catch. The diversity and regularity indices calculated for the different fishing stations varied between 1.58 and 2.27 for the Shannon and Weaver diversity and between 0.87 and 0.95 for the Piélou equitability.